Method for producing a grain-oriented electrical steel sheet excellent in glass coating characteristics and magnetic properties

摘要

PROBLEM TO BE SOLVED: To obtain an optimum amt. of uniform glass coating film excellent in adhe sion by subjecting a steel sheet to decarburizing annealing in such a manner that it is held at a specified temp. for a specified time in an oxidizing atmosphere and a nonoxidizing atmosphere and specifying the relation between the activity of citric acid in a separation agent for annealing and the annealing temp. in the nonoxidizing atmosphere. ;SOLUTION: In decarburizing annealing after final cold-rolling, a steel sheet is held at 800 to 870°C for 1 to 10min in an oxidizing atmosphere and is thereafter annealed under heating at 900 to 990°C for 10 to 60sec in an oxidizing atmosphere. In the case of 800°C, the decarburizing rate reduces, and in the case of 870°C, oxidized coating is formed to reduce the decarburizing rate. In the case of 1min, the decarburizing is not completed, and in the case of 10min, the productivity is deteriorated. In the case of 990°C and 990°C, magnetic properties can not be obtd. It is required that the relation between the activity CAA of MgO in a separation agent for annealing and the holding temp. t(°C) in the nonoxidizing atmosphere satisfies the formula. In this way, the grain oriented silicon magnetic sheet excellent in magnetic properties can be obtd.;COPYRIGHT: (C)1998,JPO